feat(cli): Allow to pass --output flag to artifact download (#726)

Signed-off-by: Javier Rodriguez <[email protected]>

Author: javirln

app/cli/cmd/artifact_download.go

@@ -1,5 +1,5 @@
 //
-// Copyright 2023 The Chainloop Authors.
+// Copyright 2024 The Chainloop Authors.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -16,14 +16,16 @@
 package cmd
 
 import (
+	"errors"
+
 	"github.com/chainloop-dev/chainloop/app/cli/internal/action"
 	pb "github.com/chainloop-dev/chainloop/app/controlplane/api/controlplane/v1"
 	"github.com/spf13/cobra"
 	"google.golang.org/grpc"
 )
 
 func newArtifactDownloadCmd() *cobra.Command {
-	var digest, downloadPath string
+	var digest, downloadPath, outputFile string
 	var artifactCASConn *grpc.ClientConn
 
 	cmd := &cobra.Command{
@@ -32,6 +34,10 @@ func newArtifactDownloadCmd() *cobra.Command {
 		PreRunE: func(cmd *cobra.Command, args []string) error {
 			var err error
 
+			if err := validateFlags(downloadPath, outputFile); err != nil {
+				return err
+			}
+
 			// Retrieve temporary credentials for uploading
 			artifactCASConn, err = wrappedArtifactConn(actionOpts.CPConnection,
 				pb.CASCredentialsServiceGetRequest_ROLE_DOWNLOADER, digest)
@@ -45,9 +51,10 @@ func newArtifactDownloadCmd() *cobra.Command {
 			opts := &action.ArtifactDownloadOpts{
 				ActionsOpts:      actionOpts,
 				ArtifactsCASConn: artifactCASConn,
+				Stdout:           cmd.OutOrStdout(),
 			}
 
-			return action.NewArtifactDownload(opts).Run(downloadPath, digest)
+			return action.NewArtifactDownload(opts).Run(downloadPath, outputFile, digest)
 		},
 		PostRunE: func(cmd *cobra.Command, args []string) error {
 			if artifactCASConn != nil {
@@ -62,6 +69,16 @@ func newArtifactDownloadCmd() *cobra.Command {
 	err := cmd.MarkFlagRequired("digest")
 	cobra.CheckErr(err)
 	cmd.Flags().StringVar(&downloadPath, "path", "", "download path, default to current directory")
+	cmd.Flags().StringVar(&outputFile, "output", "", "The `file` to write a single asset to (use \"-\" to write to standard output")
 
 	return cmd
 }
+
+// validateFlags checks if the flags are valid
+func validateFlags(downloadPath, outputFile string) error {
+	if downloadPath != "" && outputFile != "" {
+		return errors.New("cannot specify both --path and --output flags at the same time")
+	}
+
+	return nil
+}

app/cli/internal/action/artifact_download.go

@@ -35,18 +35,20 @@ import (
 type ArtifactDownload struct {
 	*ActionsOpts
 	artifactsCASConn *grpc.ClientConn
+	stdout           io.Writer
 }
 
 type ArtifactDownloadOpts struct {
 	*ActionsOpts
 	ArtifactsCASConn *grpc.ClientConn
+	Stdout           io.Writer
 }
 
 func NewArtifactDownload(opts *ArtifactDownloadOpts) *ArtifactDownload {
-	return &ArtifactDownload{opts.ActionsOpts, opts.ArtifactsCASConn}
+	return &ArtifactDownload{opts.ActionsOpts, opts.ArtifactsCASConn, opts.Stdout}
 }
 
-func (a *ArtifactDownload) Run(downloadPath, digest string) error {
+func (a *ArtifactDownload) Run(downloadPath, outputFile, digest string) error {
 	h, err := crv1.NewHash(digest)
 	if err != nil {
 		return fmt.Errorf("invalid digest: %w", err)
@@ -59,27 +61,41 @@ func (a *ArtifactDownload) Run(downloadPath, digest string) error {
 		return fmt.Errorf("artifact with digest %s not found", h)
 	}
 
+	if downloadPath != "" && outputFile != "" {
+		return errors.New("both downloadPath and outputFile cannot be set at the same time")
+	}
+
 	if downloadPath == "" {
-		var err error
 		downloadPath, err = os.Getwd()
 		if err != nil {
 			return fmt.Errorf("getting current dir: %w", err)
 		}
 	}
 
-	downloadPath = path.Join(downloadPath, info.Filename)
-	f, err := os.Create(downloadPath)
-	if err != nil {
-		return fmt.Errorf("creating destination file: %w", err)
+	// Determine output destination
+	outputPath := path.Join(downloadPath, info.Filename)
+	if outputFile != "" && outputFile != "-" {
+		outputPath = outputFile
+	}
+
+	// Open output file
+	var f io.Writer
+	if outputFile == "-" {
+		f = a.stdout
+	} else {
+		f, err = os.Create(outputPath)
+		if err != nil {
+			return fmt.Errorf("creating destination file: %w", err)
+		}
+		defer f.(*os.File).Close()
+
+		a.Logger.Info().Str("name", outputFile).Str("to", outputPath).Msg("downloading file")
 	}
-	defer f.Close()
 
 	// Calculate the checksum as we write it to a file
 	hash := sha256.New()
 	w := io.MultiWriter(f, hash)
 
-	a.Logger.Info().Str("name", info.Filename).Str("to", downloadPath).Msg("downloading file")
-
 	// render progress bar
 	go renderOperationStatus(ctx, client.ProgressStatus, info.Size)
 	defer close(client.ProgressStatus)
@@ -108,6 +124,8 @@ func renderOperationStatus(ctx context.Context, progressChan casclient.ProgressS
 	pw.Style().Visibility.ETA = true
 	pw.Style().Visibility.Speed = true
 	pw.SetUpdateFrequency(progress.DefaultUpdateFrequency)
+	// Render to stderr to avoid interfering with the output if the flag --output is set to "-"
+	pw.SetOutputWriter(os.Stderr)
 
 	var tracker *progress.Tracker
 	go pw.Render()